The rapid growth of microbreweries or craft breweries has done much to support the claim that Michigan is “The Great Beer State.” Today, the craft beer craze has moved Michigan up to fifth nationally for the number of breweries, microbreweries and brew pubs, according to the Michigan Brewers Guild.

While small brewers enjoy an economic boost from customers thirsting for more, some communities are facing new challenges trying to get a handle on whether they can treat the beer-making byproducts that get discharged into the sewers. In some cases, treatment plants are suffering hangovers from one of the newest rising stars on the industrial block.

Just how much beer can your wastewater treatment plant drink before it pukes? It’s a question few village, township or city officials thought they’d concern themselves with. But some are, especially as brewpubs and craft breweries keep popping up across the State.

While it may be cool to have a microbrewery in your town, community leaders need to know if their treatment plant has the current capacity to handle an increased load from any new industrial user. The end result for communities that don’t have a plan for managing wastewater from a brewery or any other non-residential user, could be problems meeting their wastewater treatment plant’s discharge permit or having to build new treatment capacity through costly plant upgrades.

A lot of BOD comes from Brewers Waste Products

Beer manufacturers don’t enjoy talking wastewater, but it’s a big part of doing business. Between two and seven barrels of wastewater are generated for every barrel of finished product, otherwise known as the wonderful amber- or brown-colored elixir: beer. Approximately 70 percent of the water utilized during the brewing process becomes a wastewater byproduct.

Wastewater generated at a brewery is typically high in Biochemical Oxygen Demand (BOD) and includes bottling spillage, cleaning or wash water and frequently also includes solids like spent grain, yeast and sedimentation waste. Residential wastewater has a BOD around 250 milligrams/liter. A brewery can have a BOD of 1,000-4,000 mg/L or about 4 times the strength of residential waste.

Brewers’ waste stream includes alcohol and sugars, plus wash water from cleaning floors, equipment, pipes and vessels. The wastewater from beer production is usually high in soluble biodegradable organic compounds, much higher than typical domestic wastewater.

Many large breweries, just like other significant industrial users in the state, are sometimes required to pretreat their wastewater to regular residential strength before discharging it to the sewers. Small microbreweries and brewpubs may not have pretreatment facilities. An industrial user survey, baseline monitoring survey, and Maximum Allowable Headworks Loading (MAHL) study are the first steps in determining whether new or expanded discharges can be handled and to what extent pretreatment may be required.

Complete MAHL Study For Capacity Review

Communities thinking about opening their arms to the craft beer business, or communities with breweries considering expansion, need to take some precautions to keep their treatment plants healthy and not violate their discharge permit requirements.

Communities with significant industrial users, such as breweries, that are planning to expand or that are proposing to start up a new business, should conduct a Maximum Allowable Headworks Loading . The MAHL determines the wastewater treatment plant’s capacity, estimating the maximum loading of important pollutants that can be received at plant without causing pass through, interference, or biosolids contamination. In other words, a MAHL study will determine whether there is enough capacity for the proposed new or increased wastewater load without having to expand your treatment plant.

The City of Dexter is glad it did a MAHL study before a small craft brewery completed plans to expand production and build a much larger facility.

A MAHL study had not been conducted since 1978. Many upgrades to the treatment system had occurred over the years. The true capacity of the treatment plant was unknown.

“We learned from the MAHL study how much capacity was at the wastewater plant. It was a true picture of the ability of the wastewater plant to protect the watershed,” said Dan Schlaff, Dexter’s Superintendent of Public Utilities. “It also showed we could handle additional BOD loading, which meant we could add users to our system and that translates into additional revenue.”

“By performing that MAHL, we were able to effectively expand the wastewater plant without paying for any new brick and mortar.”

The brewery in Dexter continues to expand its beer making and has increased its wastewater loading beyond the allocation identified in the MAHL evaluation. The brewery has recently constructed an aerobic/anaerobic pretreatment facility in order to comply with the approved BOD allocation identified in the MAHL. Knowing the City’s treatment plant capacity and determining the pounds of BOD that could be discharged from the brewery were key in benchmarking when the pretreatment process was needed.

About the Author

Elaine Venema, PE, is a project manager at Fleis & VandenBrink. She specializes in industrial pretreatment program consultation, wastewater treatment plant capacity analyses and infiltration and inflow studies. She is currently the vice-chair of the MWEA IPP committee and was the 2017 Industrial Pretreatment Program professional of the year. Elaine can be contacted at evenema@fveng.com, or 800.494.5202.